Plug-in solar calculator 2026: yield and saving for your German postcode

How the calculator works

The calculator goes through four steps, all listed in the calculation path under the result. First it reads the annual yield that PVGIS gives for the centre of your postcode: a 1 kWp system tilted 35° to the south, including the horizon from the terrain model. We queried all 10,815 German postcodes one by one, plus 838 grid points for maps and regions. It then converts that value to your tilt and direction using a matrix of 81 further PVGIS queries for your region. Panels hanging upright on a railing lose about a third against the optimum; east-facing panels lose a little less than west-facing ones because German mornings are clearer than afternoons.

The third step sets the output against consumption. We use the HTW Berlin load profiles: 74 households, metered minute by minute for a year. Each profile is scaled to your annual consumption and compared with generation quarter-hour by quarter-hour. Only what the household needs at that moment saves money; the rest goes to the grid unpaid. If the panels exceed the 800 VA inverter, it clips the midday peak, and that is deducted too. Finally, self-used kilowatt-hours times your electricity price give the saving, and purchase price divided by saving gives the payback.

None of this leaves your browser. The calculator never asks for a name or phone number and passes no request to a retailer or installer.

Why your postcode changes the yield

Germany is not one country as far as the sun is concerned. At the grid point near Hamburg, one kilowatt peak at 35° south yields 976 kWh a year; near Munich 1,137 kWh; the population-weighted national average is 1,057 kWh. Between the weakest and the strongest grid point lie 843 and 1,185 kWh. Working from a single German average overestimates the north and underestimates the south.

The usual German calculators ask you to pick a region from a list or your federal state. That is too coarse: within Bavaria, the Alpine foothills with their horizon and the Main valley differ by more than some neighbouring countries. PVGIS uses satellite radiation from 2005 to 2023, temperature and wind, and accounts for mountains that hide the low winter sun. Your own building or the tree opposite are not included; that is what the shading option under the calculator is for.

Self-consumption: why not every kilowatt-hour counts

A balcony system delivers between ten in the morning and four in the afternoon. In many flats, only the fridge, router and standby devices run then, perhaps 100 to 200 watts together. The simulation with 74 households shows how big the effect is: with 900 Wp tilted south in Berlin, a small household using 1,500 kWh uses 42 % of the output itself, one using 4,500 kWh uses 73 %.

This is where other calculators most often go wrong: they apply a fixed percentage to the yield. The result sounds better than what reaches your bill. If you run the washing machine, dishwasher or e-bike charger around midday you will beat our average; if the flat is empty during the day you will fall below it.

How much of the balcony power your home uses itself

Annual consumption

kWh

Panel output

Wp

Self-consumption

56 %

Output (German average, 35° south)	949 kWh
used at home	529 kWh
unpaid to the grid	419 kWh
Saving per year	€192

Compare with a battery →

Upright on the railing or tilted on a stand

Most plug-in systems hang upright on the balcony railing. That is safe and discreet but costs yield: in Berlin the same 900 Wp give 686 kWh upright facing south and 950 kWh tilted at 35°. Upright panels have an often overlooked advantage: they deliver comparatively well in winter when the sun is low, and less of a summer peak the household could not use anyway. Their self-consumption share is therefore higher.

East and west balconies are no reason to give up. Upright and facing west, a device in Hamburg still reaches 441 kWh, and the power arrives in the afternoon and early evening when use is higher. A north-facing balcony rarely pays; the calculator shows it if you choose north.

800 watts, 2,000 watts peak and batteries

Since the 2024 solar package, a device counts as plug-in solar (Steckersolargerät) if its panels total at most 2,000 Wp and the inverter at most 800 VA (section 8(5a) EEG). More panel output on an 800 VA inverter is therefore allowed. It gives more power in the morning, evening and winter; at midday the inverter clips. With 1,800 Wp tilted south in Berlin, 370 kWh of 1,904 kWh are lost that way.

A battery on the DC side catches exactly that peak and releases it in the evening. With 2 kWh, the self-used power of that system rises from 698 to 1,149 kWh a year, a gain of €163. Whether that pays depends on the extra cost; the plug-in solar battery calculator compares both cases side by side.

Registration, meters and rented flats

The only registration is in the Market Master Data Register, within one month of commissioning (section 5(5) MaStRV). It takes about a quarter of an hour; a battery is added as a second unit. On 15 October 2026, 1,532,438 plug-in devices in operation were registered there nationwide. An old electromechanical meter may keep running until it is replaced, even if it turns backwards when you export (section 10a(3) EEG); the metering operator fits the bidirectional meter without you ordering it.

Since 17 October 2024 (Federal Law Gazette 2024 I no. 306) tenants have a right to permission (section 554 Civil Code) and flat owners to a decision by the owners' association (section 20 Condominium Act). You pay no VAT on panels, inverter or battery (section 12(3) VAT Act), and the saving is not taxable income.

Values and assumptions for 2026

Examples from five cities

When plug-in solar does not pay

A device on a north balcony, a balcony shaded by the building opposite, a household that is empty all day with little base load: then the saving drops below 50 euros a year and payback takes longer than the inverter lasts. A large battery on a small device rarely pays either; in winter it hardly fills. The calculator shows such cases honestly instead of flattering them.

If you own a house with a free roof, run the numbers for a full system too: the rooftop PV calculator uses the feed-in tariff for the commissioning period and the 60 per cent limit of the 2025 solar peak law.

All calculators at a glance

• Plug-in solar with battery: with and without, side by side.
• Rooftop PV calculator: self-consumption and feed-in.
• Home battery calculator: what a battery adds to a roof system.
• Feed-in tariff: the rate by commissioning date and size.
• PV yield by postcode: kWh per kWp for any orientation.
• How many kWp?: the most economic system size.